Inner tube for pneumatic tires.



1. B.\Z|MDARS. INNER TUBE FOR PNEUMATIC TIRES.

APPLICATION FILED Ivi/W13, |918.

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To all bottom may concern.'

Be it known that ll, donn ld. Mineras, a citizen of the UnitedStates,residing at San Francisco, in the county of San Francisco and State ofCalifornia, have invented new and useful Tmprovements in Tnner Tubes forPneumatic Tires, of which the following is a specilication.

The present invention relates to improvements in inner tubes forpneumatic tires, the present application being a division of anapplication for pneumatic tires led by me Sept. 7, 1917, Serial No.190,108.

Tn the accompanying drawing, Figure 1 is a cross section of a tireconstructed in accordance with my invention; F ig. 2 is a similar viewof an inner tube thereof detached. y

Novel features herein disclosed butV not claimed are claimed inco-pending divisional applications.

Referring to the drawing, 1 indicates one of the spokes of a Wheeltowhich is secured a rim 2 having on one side an outwardly extendingflange 3 and on the other side a shoulder 3L the flange 3 forming agroove 3*, the purpose of .which is to receive a retaining ring, nothere shown, it not being part of the present invention, and the shoulder3a together with the retaining ring securing the tire to the rim. Aroundsaid rim are arranged the two sections 4e of a hollow sheet metal ring.The hollow sectionst have inner ends 7 abutting against each other, andbroad outer ends 3 which extend, in general direction, in planestransverse to the axis of the wheel, and each section has an innercylindrical side contacting with the cylirn drical surface of the rim,and an outer side 6 which is concave in cross-section so that the sides6 of the two sections of the metal ring have a substantiallysemi-circular form in cross-section.

Said ring sections d are secured together by long bolts 9, the heads 10of which. are received in a groove 11 in the outer wide end il of onering section Il, while nuts 13 are screwed upon the other ends of saidbolts and are received in a corresponding groove 1t in the wide end 8 ofthe other ring section t.

Surrounding the hollow ring sections dand received in the concave outersides 6 thereof is an endless pneumatic tube 16 of canvas, indatcd inthe usual manner, having specification or Ietters Patent.

Patented dan., ltd, 19119.,

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a thin inner facing 1'? of soft rubber and secured to a thiclr outercoating 18 of a por tion thereof, also of soft rubber, .which variesgreatly in thickness. The coating 18 does not extend completely aroundthe tube 16 and it is not interposed between the tube 16 and the hollowring sections d, but it begins oneach side of the tube 16 where thesides of said tube leave the ring sections 4: and fits in the spacebetween the sides of the tube 16 and the side portions of a tread orcasing 19.

Said casing 19 is secured to the ring sec tions 4l in the followingmanner: Each ring section is formed in its wide side with a circulargroove 21, and the edges of the casing are formed .with beads 22 of'metal or other rigid material, which enter said grooves. They areretained therein by means lof rings titl bfi

23, which are secured to the wide ends 8 of tt the ring sections l byscrews 24:, and which have inwardly extending portions 26 fittingtightly in said grooves 21 and wedging the `beads therein and outwardextensions 27,

which overlap the inner edges of the casing and retain its inner edgesin the grooves 21. The casing is formed with a tread 28 having, embeddedin rubber, layers of canvas 29, and similar in general character tothose at present in use.

Between the tread and the pneumatic tube is interposed a protecting ring31. This ring comprises, in order proceeding from the outside inward,irst, an outer ring 32 of soft rubber, then a circular series ofrectangular protecting blocks (with edges rounded olf and their longermeasurement being cross- ,wise of the tire), these blocks being of woodor other impenetrable material, spaced slightly from each other, then aninner ring 34 of soft rubber, then another series of blocks 36 ofimpenetrable material spaced slightly from each other, and then an innerring or covering 35 of soft rubber. Said rings 32. 34, 35 are allconnected with each other at the edges, so that the blocks 33 and 36 arecompletely inclosed, and said rings and blocks are all cemented togetherby rubber. The blocks of each series are staggered relatively to thoseof the other series, so that the spaces between the blocks of eachseries register with the central `ortions of the blocks of the otherseries. t will thus be seen that it is impossible for a nail or othersharp instrument to penetrate through tte both series of blocks. Theblocks of theinner series are preferably convex so as to be thickesttoward the center'of their longer measurement, but also slightly concaveat the centers of their inner surfaces as shown at 37, and all theblocks, both at their ends and at their edges `where they are spacedfrom each other, are rounded so as to avoid any cutting of the rubber incontact therewith. The rubber intervening between the inner tube 16 andthe casing 19, or between the inner tubes and the blocks 36, variesgreatly in thickness, being thinnest next to the middle portions of thesides of the tube 16 and thickest next the ends of the blocks 36.

lt will be seen that my improved tire is not subject to punctures suchas are common with ordinary pneumatic tires, and that the only partexposed to wear is the tread, which can be renewed at a comparativelylow cost when worn out.

The blocks 36 of the inner series have fluted portions, the purpose ofwhich is to .take up slack in the periphery of 'the inner tube 16`whichexists when said tube is not fully inflated, so as to assume a circularform; the convex shape of the inner series of blocks is to providegreater and quicker resiliency when pressed againstv said tube 16. `Whenthe tube is fully inflated it will assume a substantially circular formin cross-section, as shown in dotted lines.

It will be seen that my invention differs from prior constructions inthat the pneumatic tube is inexpansible as distinguished from the softrubber tubes heretofore used for pneumatic tubes. lVhen inflated itassumes a form as nearly as possible circular in cross-section which, bythereby increasing the area within the tube, takes up all the slack inthe cavity left between the flexible shield and the rim.

lt will be observed that my invention differs from ordinary pneumatictires in that there is interposed, between the inner tube and the treadof the tire, material that is, for the most part, inelastic, ascontrasted with the large amount of' rubber used on the outside orinside of the tire in some present day constructions. The contractionand expansion of this rubber in these old constructions, relieves, to acertain extent, the inflated inner tube of lts Work 1n contracting andexpanding, but with a greater loss of energy, on account of the factthat air can contract and expand much more readily and with much lessloss of energy than solid elasticmaterial. Consequently, it is anadvantage that no attempt should be made to take up the shocks, causedby the running on the road-bed, by means of rubber, but that the Wholeof the Work should be thrown upon the elastic air Within the inner tube,and this I accomplish in my invention by interposing as much as possibleonly inelastic material between the inner tube and the outside of thetire, the intervening portions of rubber only being of sufficientthickness to form a container for the different pieces of impenetrablematerial to hold the same in their proper relations and to render theshield flexible in a circumferential direction, thus constituting asingle, flexible, continuous, annular belt.

Another purpose of my invention is to providel a tire that will notrequire an outer casing with stiff heavy sides as those of the casingsin present use or With sides extending` inwardly so that they in'themselves form the circle inclosing the inner tube, or with the heavyelencher or heavy bead construction, but which will instead permit ofand have au outer casing or shoe constructed with relatively thinflexible sides, which need extend only a short distance beyond thecenter of the circumference of the inner tube, and are there removablyfastened `to the metal tire sections, thus providing a highly flexibleand inexpensive and easy replaceable wearing shoe.

In a resilient tirel` an inexpansible inner pneumatic tube of sufficientstrength in itself to withstand the necessary air pressure without theassistance therefor of an outside casing or shoe, and having rubberhousing` around the saine coniparatively thin on its inner periphery,and thicker on its sides and outer periphery, said housing being on theouter periphery in form slightly concave so as to form a seat for aprotector ring or shield, and a protector ring on said seat.

JOHN B. ZIMDARS.

